The copying and redistribution of commercial imagery, audio and video productions has long been a cause of lost revenues to the creators/producers of such material. The advance of technology has not only expanded the means of legitimate distribution for audio and visual/video works, but has also made it easier to copy these materials for unauthorized purposes. In addition, there is a need to monitor, verify and track broadcasts and other distributions of this content.
Various methods have been developed to eliminate or limit both sophisticated and unsophisticated illegitimate distribution as well as to monitor distribution. Some of these methods rely on physical means. Others employ an auxiliary embedded signal to control, monitor and track usage of the content.
In accordance with preferred embodiments of the present invention, a multi-bit auxiliary message (sometimes termed a “digital watermark”) is robustly embedded directly into the audio signal. Hardware or software systems can then read this message and, for example, and control, monitor or track usage of the content.
Key practical issues are addressed whereby the perceptual impact of this added message can be adjusted—both overall and as a function of the underlying audio content. In addition, robustness to various forms of distortion are addressed in a manner superior to the prior art.
One combination recites a method comprising: (a) obtaining data representing audible portions of audio or representing picture portions of video; (b) using a programmed electronic processor, determining identifying information from the obtained data by computing a frequency transform to produce frequency transform data, and processing the frequency transform data to derive a pattern, and using the pattern as the identifying information for the audio or video; and (c) using the identifying data to facilitate purchase or license of the audio or video. A related method recites that the processing comprises determining a location of a feature in the frequency transform data. Another related method recites that the processing comprises applying a thresholding to magnitude values in the frequency transform data. Still another related method recites that the using the pattern as the identifying information identifying comprises derives an index from the pattern. And another related method recites that the pattern is steganographically decoded from the frequency transform data.
Another combination recites a method comprising: obtaining an audio or video data feed, the data feed representing audible portions of an audio signal or picture portions of a video signal; using a programmed electronic processor, analyzing the data feed to determine potential pattern matches with previously determined patterns; upon determining a potential pattern match, and using a programmed electronic processor, performing a more refined analysis relative to said act of analyzing to determining identifying information; and using the identifying information to facilitate purchase or license of the audio or video.